It is known that in making vehicle tires, for example for automobiles, that manufacture of a so-called carcass is first achieved by successively assembling several different components.
In other words, the different carcass types included in a production range can be distinguished from one another depending on the presence thereon of the various accessory components and/or the typology of the accessory components themselves.
By way of example, when carcasses for tubeless tires are to be produced, that is tires that in use do not require the presence of an inner tube, the main components can be considered to include a so-called “inner liner” that is a layer of elastomeric air-impervious material, a carcass ply, a pair of annular metal elements, commonly referred to as bead cores, around which the opposite ends of the carcass ply are folded, as well as a pair of sidewalls made of elastomeric material, extending over the carcass ply at laterally opposite positions. The accessory components may in turn comprise of one or more additional carcass plies, one or more reinforcing bands for overlying the carcass ply or plies at the areas turned up around the bead cores, chafer strips, and others.
As disclosed in U.S. Pat. No. 5,554,242, two stage tire building with a first stage tire building drum in combination with a second stage tire building drum is well known and established in the art with the building drums being both in line and offset from each other. It is further known to have two-stage tire building with a single drum swinging between the first stage position and second stage position where a band builder is in line with the first stage building drum. For this system, individual breaker application and single piece tread rubber are applied at the second stage while components such as apex, chafers and shoulder wedges are applied at the first stage. The above components are made in separate operations and stored for use as needed in the two-stage building process.
While the two-stage building process in its separate stages accommodated servers for the various components, it presented the problems of requiring a large work area for the two separate positions and the need to coordinate the separate functions as well as bringing all of the components together at the proper stations. As a result, the components were often stored and became subject to aging, sometimes losing their tack, for example, during the handling of the individually applied components. Moving the tire subassemblies from one stage to another has been a highly labor intensive operation even with the use of mechanical servers to assist operators in placing the components on the tire on the first and second stage drums. As a result, the operation was costly.
U.S. Pat. No. 5,354,404 discloses a system for assembling green tires with a two-stage process where the assembly is automatic and requires a small amount of floor space. While this system, has overcome some floor space problems, its output is still limited.
It has been known in the prior art, as disclosed in U.S. Pat. No. 2,319,643, to manufacture tires on a line with a plurality of building drums that are chucked up at each station.
Also, as disclosed in U.S. Pat. No. 1,818,955, tires can be manufactured on a line with a plurality of building drums “arranged in a train or series and a connecting means is provided for translating the cores from one device to the next.” The connectivity between the tire cores (building drums) leads to the inability to change the machine to accommodate various sized tire constructions. U.S. Pat. No. 3,389,032 also discloses a system using a large number of building drums which are interconnected.
Further, as disclosed in U.S. Pat. No. 5,354,404, there is illustrated another system for manufacturing tires on a line with a plurality of building drums “arranged in a train or series and a connecting means is provided for translating the cores from one device to the next.” The connectivity between the tire building cores leads to the inability to change the machine to accommodate various sized tire constructions.
In modern production processes, the assembling of the different components is carried out in automated plants including a plurality of assembling drums moved following a precise working sequence in accordance with the manufacturing process to be executed. For example, as disclosed in U.S. Pat. No. 5,411,626, these plants can consist of a plurality of workstations disposed consecutively in side by side relation, each of which lends itself to carry out the application of a predetermined component onto the assembling drums that in turn are brought in front of it.
EPO 0105048 discloses a tire assembly means employing a conveyor to transport a plurality of tire building drums to a plurality of applicator stations wherein various components are applied to the tire building drums at the various applicator stations in order to fabricate a tire when the tire building drums have made a complete transversal of the conveyor, wherein the tire building drums are maintained in an angled relationship with respect to the conveyor and the applicator stations.
In particular there are primary workstations intended for application of the main components, which are always active, irrespective of the carcass type being produced. Alternated with the various primary workstations, there are one or more auxiliary workstations intended for application of accessory components, if required. The activation or deactivation state of these auxiliary workstations stations depends on the carcass type.
The problem with these prior art manufacturing systems is that the location and position of the building drums was not precise enough to ensure that the tires being constructed were of adequate uniformity for the requirements of present day high performance tires. That is, while the tire building drums moving along the assembly path were stopped at a stop position at each work position, there is no teaching or suggestion of how the position of the tire building drum was positioned at a precise position. Further, it appears that the power to operate each building drum was carried aboard each drum. This would suggest that each drum is more complicated and expensive to produce.
It is well known that the components of most pneumatic tire constructions must be assembled in a way, which promotes good tire uniformity in order to provide proper tire performance. For example, a tread which “snakes” as it goes around the tire circumference will cause wobbling as the tire is operated. For example, a carcass ply which is lopsided (longer cords on one side of the tire than the other side) can cause a variety of tire non-uniformity problems including static imbalance and radial force variations. For example, a tire which is not meridionally symmetric (e.g., tread not centered between beads) can cause a variety of tire non-uniformity problems including couple imbalance, lateral force variations, and conicity. Therefore, in order to meet typical tire performance requirements, the tire industry generally expends considerable effort in producing tires with good uniformity. Tire uniformity is generally considered to mean tire dimensions and mass distributions which are uniform and symmetric radially, laterally, circumferentially, and meridionally, thereby producing acceptable results for measurements of tire uniformity including static and dynamic balance, and also including radial force variation, lateral force variation, and tangential force variation as measured on tire uniformity machines which run the tire under load on a road wheel.
Although certain degrees of tire non-uniformity can be corrected in post-assembly manufacturing (e.g., by grinding), and/or in use (e.g., applying balance weights to the rim of a tire/wheel assembly), it is preferable (and generally more efficient) to build-in tire uniformity as much as possible. Typical tire building machines comprise a tire build drum around which the tire components are wrapped in successive layers including, for example, an inner liner, one or more carcass plies, optional sidewall stiffeners and bead area inserts (e.g., apex), sidewalls and bead wire rings (beads). After this layering, the carcass ply ends are wrapped around the beads, the tires are blown up into a toroidal shape, and the tread/belt package is applied. Typically the tire build drum is in a fixed location on the plant floor, and the various layers of components are applied manually or automatically using tooling registered to reference points on the fixed drum in order to ensure component placement with the desired degree of precision. The tooling is generally fixed relative to the tire building drum, for example a guide wheel on an arm extending from the same frame (machine base) which supports the tire building drum.
The prior art, as discussed herein still has problems of enabling the building of tires with complicated construction, such as runflat tires, to be built on a single manufacturing line that is capable of being easily changed to accommodate different constructions sizes.
According to the one prior art invention there is disclosed in patent EPO 1295701 a method for simultaneously building a plurality of tire carcasses. The method comprises the tire building steps of establishing a sequence of at least three and up to ten workstations; advancing at least three disconnected cylindrically shaped tire building drums along a working axis extending through the at least three workstations; and applying one or more tire components to the tire building drums at each of the workstations. Then the resulting flat built green tire carcass is removed at the last of the workstations. Finally, the tire building drum is advanced from the last workstation after the flat built green carcass has been removed to the first workstation. Thereafter, the belt and tread package is disposed about the cylindrical or flat built green tire carcass, expanding the tire carcass into a tread and belt to form a green tire.
According to that invention, the tire building drums were disconnected from each other and independently advanced along the linear working axis extending between the workstations. Each of the disconnected tire building drums were individually advanced along the working axis so that the axis of rotation of each tire building drums remains aligned with the linear working axis.
According to that invention, the plurality of disconnected tire building drums can be simultaneously advanced along a working axis with individual, self propelled devices to which the tire building drums are mounted from one workstation to another. The tire building drums are advanced along the working axis so that an axis of rotation through the building drum is maintained at a constant predetermined height and location and in parallel alignment with the working axis.
According to that invention, an intake server is located at each of the workstations for operating the tire building drums. The intake servers were coupled to the building drums while maintaining the axis of rotation through the building drums at the constant predetermined height and location and in parallel alignment with the working axis. The intake server at each of the workstations move from their normally retracted position outward across the working axis into a position to couple to that tire build drum. Then the building drums were uncoupled from the intake servers after the tire component(s) had been applied to the building drums. Next, the intake server at each of the workstations were retracted to their normally retracted position, prior to the now uncoupled tire building drum advancing to the next workstation.
According to the invention, the step of applying one or more tire components to the tire building drums at each of the workstations included applying the tire components to the tire building drums while maintaining the axis of rotation through the building drums at the constant predetermined height and location and in parallel alignment with the working axis. This was accomplished by providing one or more application drums at each of the workstations for applying the tire component(s) to the building drums.
The application drums are moved from their normal retracted position away from the working axis to a location where the tire components can be applied to the building drums while maintaining the axis of rotation through the building drums at the constant predetermined height and location and in parallel alignment with the working axis. Then the application drums are retracted at each of the workstations to their normally retracted position, prior to advancing the tire building drum to the next workstation.
A primary limitation of the above-described prior art method of automated tire assembly is believed to be the applying of the components for the carcass assembly on a flat building drum and then inflating said drum to a toroidal shape prior to applying the belt tread assembly.
Another primary limitation is the application of the tread belt assembly to the toroidially shaped carcass means. The green tire assembly must be inflated and further expanded to fit the internal surfaces of the mold cavity.
In essence the entire automated assembly resulted in a most conventional green tire carcass and belt assembly to result with all the inherent deficiencies in the manufacture flat tire building methods.
The present invention proposes a novel way to build a tire in a shape closely simulating a finished product while achieving high levels of automation and precision part placement.
Another objective of the present invention is to achieve the ability to change tire sizes in the line to permit a variety of sizes to be built simultaneously without disrupting the line for size changeovers. This capability enables tires to be built in an automated way in lot sizes as small as one tire.
Another objective of the present invention is to provide a cure station so that the tire is completed from start to finish from raw components to a cured tire within the manufacturing module.